The present invention relates to a medical instrument for endoscopic removal of the saphenous vein, having an elongated shaft which has at the distal end a spatula tip and in whose proximal region is arrange a laterally projecting handle; and further having an endoscopic optical system which has an eyepiece cup that is arranged at the proximal end of the instrument.
The present invention further relates to a method for endoscopic removal of the saphenous vein.
An instrument of the aforesaid kind is known from the company document xe2x80x9cEndo World,xe2x80x9d CHIR No. 4-D, 1997, published by Karl Storz GmbH and Co., Tuttlingen, Germany. An instrument of this kind is illustrated on page 3 of this document under the designation xe2x80x9coptical retractor.xe2x80x9d
The saphenous vein (vena saphena magna) is a long leg vein that runs on the medial (i.e. inner) side of the leg from the inside of the ankle along the lower leg and thigh to the groin.
The saphenous vein is often removed for use as a transplant in cardiac and vascular surgery. In conventional surgical methods for removal of the great saphenous vein, either a single long incision is made along the inner side of the leg, or several short incisions, separated from one another, are made. Using instruments (called xe2x80x9cvein dissectorsxe2x80x9d) introduced through these incisions, the saphenous vein is detached from the surrounding connective tissue and its lateral branching vessels. The detached and isolated vein is then removed through a single long incision or several separate incisions entails the risk, however, of injury to the medial lymph bundle and thus infection of the operative area.
The article xe2x80x9cMinimally invasive, video-assisted vein harvesting for cardiac and vascular surgical proceduresxe2x80x9d by Lutz et al. (1997), in European Journal of Cardio-Thoracic Surgery 12, pp. 519-521, describes an alternative method for removing the saphenous vein, in which the vein is removed using minimally invasive techniques under endoscopic observation. For this purpose, only a single small (2-3 cm long) incision is introduced in the vicinity of the knee joint. Through this incision, the instrument cited initially is introduced upward along the thigh portion of the vein into the groin, and downward along the lower-leg portion of the vein to the inner ankle. The vein is thereby detached from consecutive tissue and lateral branching vessels, and the entire vein is pulled out through the single incision in the knee region. This endoscopic removal technique is gentle on the tissues, as compared to the earlier removal method described above, because only the one incision is required, and the patient""s postoperative discomfort and the risk of surgical infection are much lower. In addition, removal using this newer method always takes place under endoscopic visual supervision.
The instrument known from the aforementioned German company document xe2x80x9cEndo World,xe2x80x9d which is suitable for the procedure described above, has an elongated shaft that carries at it proximal end a laterally projecting handle and an eyepiece cup belonging to an endoscopic optical system. The shaft is configured from the proximal to the distal endxe2x80x94at which a narrow spatula tip, tapering in the distal direction and slightly curved, is configuredxe2x80x94as an approximately kidney-shaped trough for external reception of an optical shaft of the endoscopic optical system, i.e. the endoscope shaft rests on the outside of the shaft in the trough. The endoscopic optical system, made up of the optical shaft and eyepiece with eyepiece cup, can be removed from the shaft by pulling the endoscopic optical system in the proximal direction off the shaft, through an attachment segment of the handle. The shaft of the medical instrument is approximately 30 cm long in order to be able to reach the ends of the vein from the single incision in the knee region.
With the known instrument, the handle is attached to the shaft in such a way that the shaft is widened in the region of the handle, i.e. the outer side of the instrument, facing away from the handle, has a step in the region of the handle extension. In addition, the eyepiece cup is arranged at the proximal end of the shaft in such a way that the longitudinal center axis of the eyepiece cup runs as a straight-line coaxial extension of the longitudinal center axis of the instrument shaft, so that the eyepiece cup extends circumferentially beyond the shaft on all sides.
This configuration of the known instrument is, however, disadvantageous in the context of a surgical procedure for removing the great saphenous vein.
This is because in the endoscopic procedure for removal of the great saphenous vein, the instrument is introduced through the incision in the knee region and is pushed upward along the vein to the groin, and downward into the ankle region.
In order to allow the entire vein to be removed through a single incision, the entire length of the medical instrument must be utilized, since the instrument must be advanced from the knee to the groin and down to the ankle along the vein. Since the vein runs just beneath the skin, the shaft of the instrument must be advanced almost parallel to the skin surface, so that the segment of the shaft located outside the incision as the shaft is advanced along the vein must be pushed forward while being held closely as possible against the leg.
With the known instrument, the fact that the attachment segment of the handle and the eyepiece, as described above, project laterally in the proximal region of the shaft that remains outside the body means that the instrument is considerably widened in its proximal region above the shaft on the outer side of the instrument that rests against the leg. This widening, however, prevents the instrument from lying close to the patient""s leg, with the consequence that the spatula tip cannot be slid forward along the vein just beneath the skin surface. Such is the case, at least, when the instrument has already been advanced a long way into the operative area. Because of the widening of the instrument in the proximal region on the outer side facing away from the handle, it is thus almost impossible to guide the spatula tip deep into the operative area along the saphenous vein while still parallel to the skin surface. Instead, the spatula tip penetrates into deeper tissue and can thereby result in undesirable damage to uninvolved tissue. To eliminate this risk, the known instrument can be used only up to a certain insertion depth of the shaft into the operative area. A further disadvantage of the known instrument furthermore consists in the fact that with increasing insertion depth of the shaft into the incision, the camera connected to the eyepiece for observation of the operation through the endoscopic optical system is, beyond a certain insertion depth, in such close contact against the patient""s leg that the camera, whose housing dimension transverse to the shaft axis is wider than the shaft itself, prevents parallel subcutaneous advancement of the instrument. The camera furthermore prevents the introduction of further auxiliary instruments into the incision. Handling of the known instrument is thus also made more difficult.
U.S. Pat. No. 5,667,480 also discloses an instrument and method for endoscopic removal of the saphenous vein in which the aforesaid disadvantages also exist, namely that the shaft is widened in the region of the handle attachment, and that the eyepiece is axially aligned.
U.S. Pat. No. 5,373,840 discloses a comparable instrument, having a handle protruding laterally from the shaft and having an integrated endoscopic optical system that transfers the observed image directly to a monitor. An eyepiece can also be provided in conventional fashion instead of the monitor, but there is no indication as to how the eyepiece would then be arranged.
Against this background, it is the object of the present invention to make available a medical instrument of the aforesaid kind which makes it possible to remove the great saphenous vein through the smallest possible incision in the patient""s body, the spatula tip of the instrument is to be insertable into the incision and along the vein just beneath the skin surface over as much as possible of the entire insertion depth of the shaft.
This object is achieved, in terms of the medical instrument cited initially, in that the handle is joined to the shaft in such a way that an outer side of the instrument facing away from the handle has a continuous straight surface that, from the distal to the proximal end, is substantially free of projections, and that the shaft-handle plane is inclined with respect to the shaft-eyepiece cup plane at an angle of less than 90xc2x0.
As a result of the design according to the present invention, the medical instrument receives on its outer side facing away from the handle a uniform surface, running from the proximal end to the beginning of the distal spatula tip, that is free of projections and thereby allows the proximal region of the instrument to lie in close contact against the outer surface of the patient""s leg, and thus readily permits the shaft of the spatula tip to be slid along the vein just beneath the skin surface. Because the eyepiece cup is arranged, according to the present invention, in laterally oblique fashion, it also no longer extends beyond the outer side of the instrument facing away from the handle.
The design according to the present invention, having an outer side that is free of projections, makes it possible to introduce the medical instrument into the patient""s leg over the entire length of its shaft. Since there are no enlargements, ridges, or the like in the proximal region of the instrument, the instrument can be introduced in closely contacting fashion in the region of the incision and held in that fashion during the operation. The instrument according to the present invention thus makes it possible, even with a small incision, to utilize the entire length of the shaft.
This uniform surface also allows easy insertion of further auxiliary instruments, for example vein dissectors, dissecting or grasping forceps, scissors, ligature loops, or the like, without requiring a larger incision.
The aforesaid outer side of the medical instrument according to the present invention need not be continuously integral. It can be constituted from multiple surfaces, arranged one behind another, which belong to different constituents of the instrument (such as the endoscope, handle, and shaft that optionally are detachable from one another. What is critical in this context is that the aforesaid outer side is free of projections that protrude distinctly beyond the outer periphery of the shaft. The medical instrument is thus of substantially flat configuration on the side resting against the patient""s leg, and the instrument is slid into the incision along the patient""s leg on that outer side.
A further advantage of the instrument according to the present invention is the fact that the physician can always bring his or her eye to the eyepiece cup in unimpeded fashion regardless of the insertion depth of the instrument, since the eyepiece cup stands out from the shaft and thus from the patient""s leg. In the event a camera is used on the instrument eyepiece, introduction of the auxiliary instruments is advantageously no longer impeded by the attached camera. As an additional result, handling of the instrument according to the present invention is advantageously improved.
The method of the present invention includes the step of providing an instrument according to the present invention.
In a preferred embodiment, the handle has an attachment segment that is configured in the upper region in the form of a sleeve which fits over an axial portion of the shaft with the least possible material thickness on the outer side of the shaft facing away from the handle.
This feature has the advantage on the one hand of bringing about a stable join between the handle and the shaft, and on the other hand of keeping the outer side of the instrument, facing away from the handle, free of shoulders, steps, or protrusions.
In a further preferred embodiment, a longitudinal center axis of the eyepiece cup forms an angle in the range from 30xc2x0 to 60xc2x0, preferably 45xc2x0, with the longitudinal center axis of the shaft.
If the eyepiece cup is arranged to protrude at an angle within this range, it is particularly convenient for the physician to look into the eyepiece cup from the side of the instrument facing away from the patient""s body.
In a further preferred embodiment, the eyepiece cup is arranged on an eyepiece housing of the endoscopic optical system which has an outer side, facing away from the eyepiece cup, that approximately aligns with the outer side of the shaft facing away from the handle.
The advantage of this feature is that the aforesaid outer side of the eyepiece housing constitutes a shoulder-free prolongation of the outer side of the instrument facing away from the handle, thus improving guidance of the instrument along the leg by way of the extended contact surface constituted by the eye-piece housing.
In a further preferred embodiment, the shaft is configured as a circumferentially closed hollow shaft for reception of an optical shaft, extending to the spatula tip, of the endoscopic optical system.
The advantage of this feature is that the optical shaft of the endoscopic optical system received in the shaft experiences improved guidance upon insertion along the shaft and improved retention in the shaft, thus facilitating installation of the endoscopic optical system on the instrument shaft. A closed shaft having an internally located optical shaft moreover has the advantage that the outer surface of the shaft can be configured to be smooth and have no sharp edges all around, thus allowing the shaft to be more easily advanced in the operative area. The optical shaft is moreover protected from contamination. In addition, further auxiliary instruments can be introduced into the instrument shaft in order to remove connecting tissue and detach the vein. All these auxiliary instruments can then be enclosed by the shaft and thus also protected from contamination. Above all, the instruments experience xe2x80x9cnon-jerkyxe2x80x9d guidance along the shaft toward the distal end.
In a further preferred embodiment, the outer side of the shaft facing away from the handle is flat in cross section, viewed toward the longitudinal center axis of the shaft, with a slight concave curvature.
Since the outer side of the shaft facing away from the handle is guided along the outer surface of the leg upon insertion of the instrument, the advantage of this feature is that this outer side rests in planar contact against the leg and thus al-lows improved guidance of the shaft along the leg. The slightly concave configuration additionally has the advantage that the segment of the shaft already introduced into the incision experiences, with the curvature, a certain positive guidance along the vein.
In a further preferred embodiment, an outer side of the shaft facing toward the handle is convexly curved in cross section when viewed toward the longitudinal center axis of the shaft.
The advantage of this feature is that the optical shaft received in the shaft automatically assumes a centered position in the instrument shaft in the curvature upon insertion into the shaft, thus further facilitating installation of the endoscopic optical system on the shaft.
In a further preferred embodiment, the spatula tip has a spoon-shaped curvature that opens toward the side of the instrument facing away from the handle.
The advantage here is that as the instrument is slid forward, an operative cavity, which can be easily illuminated and observed through the endoscopic optical system, is formed in the region of the distal spatula tip. The spoon-shaped curvature of the spatula tip also protects the region in which the distal elements of the auxiliary instruments, for example mouth parts of forceps of the like, are actuated.
In a further preferred embodiment, the spatula tip has a lateral widening so that it extends beyond the shaft, at least on one side, transversely to its longitudinal center axis.
The advantage of this feature is that the operative cavity created by the spatula tip as the shaft is advanced is enlarged as compared to the operative cavity created by the spatula tip of the known instrument. An enlarged operative cavity has the advantage that more space is created for the mouth parts of the auxiliary instruments.
In a further preferred embodiment, the spatula tip tapers toward the distal end.
The advantage of this tapering is that it facilitates advancement of the instrument according to the present invention through the bodily tissue.
In a further preferred embodiment, the handle projects from the shaft obliquely toward the distal end of the shaft.
The advantage of this feature is that the instrument can be introduced into the incision, at the handle which is thus inclined in the insertion direction, with a straight hand position and thus forcefully, thus further improving handling of the instrument according to the present invention.
The longitudinal center axis of the handle and the longitudinal center axis of the shaft define a first plane and the longitudinal center axis of the eyepiece cup and the longitudinal center axis of the shaft define a second plane. The first plane is inclined with respect to the second plane at an angle of less than 90xc2x0, which, looking down the length of the shaft from its proximal to its distal end, may be in either a clockwise or a counter-clockwise direction.
Often, though not always, it will be more advantageous to have the first plane inclined with respect to the second plane at an angle of 0xc2x0. The advantage of this angle is that the handle and the eyepiece cup protrude from the shaft in a single plane, thus achieving the advantage that after introduction of the instrument, it can also be rotated about its longitudinal axis without thereby encountering the eyepiece cup as an obstacle. Rotation of the instrument as it is advanced may be used, for example to deflect side branches of the saphenous vein as the instrument is advanced.
The degree and direction of the angle that would be most advantageous, however, may depend upon various factors, such as whether the physician is right-handed or left-handed, into which leg the instrument is being inserted, the physician""s operating style, or a preference with respect to achieving maximization of both viewing and rotational capability. Often, though not always, this angle will be less than 10xc2x0.
Further advantages are evident from the description below and from the appended drawings.
It is understood that the features mentioned above and those yet to be explained below can be used not only in the respective combinations indicated, but also in other combinations or in isolation, without leaving the context of the present invention.